Electric furnace.



NATHUSUS ELECTRIC FURNCEl APPLICATION FILED MAY 6,190a- 983,303, y Patented Fb. 7, 1911.

f 4. 2 SHEETS-sum1 1 .J9/venan Z N ff .1,

NATHUSUS.

BLEGTRIG PURNAGE.

APPLICATION FILED MAY G, 1908. 983,303. Patented Feb?, 19H.

2 SHEETS-SHEET 2,

HANS NAT-ISIUS, OF FRIEDENSHTTE, MORGENROTH, GERMANY.

ELECTRICy FURNACE.

Specication of Letters Patient.

Patented Feb. 7, 1911.

Application filed May 6, 1998. Serial No. 4315158.

To all whom fit may concern:

Be it .known that I, HANS Na'rnnsins,

' engineer', subject of the King of Saxony, re'- generally rest only on the slag cover.

siding at Friedenshtte, near Morgenroth, in Germany. have invented new and useful Improvements -in Electric Furnaces, of which the following is a specification.,

This invention relates to an electric furnace which is' suitable. for all operations generally'carried outfn electric furnaces, more particularly for refining and manufacturing steel.

' As is well known, the manufacture of good steel depend-s on a good and uniform heating of the steel bath and on thev obtainment of a slag which should be as hot and as fluid as possible and therefore most suitable for reaction. Existing furnaces do not conlplywvith ,these requirements, partly owing to the use of a small melting hearth, so that the steel bath has only a small surface of contact with the slag cover. .Furthermore the expulsion of gases from the steel bathtakes place. only with ditiiculty, and in performing the necessary work in the .surface of the bath, such as the frequent removal of the .slag by means oflong iron Arods or the stirring of the vmetal bath by means of wooden or steel bars or the distribution of the required additions on the surface ofthe bathete., dilticulties aremet with, because in such cases the electrodes .\c cordingly they are usually raised. which results in the bath heilig cooled, as no current is passing through it at such time. On the other hand the carrying out ofthe above work while current is passing would be difficult and complicated, as the tools may come into contact with the electrodes and sometimes displace them, and the bath is liable toget dirty owing to the broken off pieces ofthe electrodes falling into it. apart from the fact that contact with such electrodes is dangerous to the life Aof the attendants.

The above disadvantages are obviated in the furnace according to this invention by the electrodes being Vdistributed over the whole circumference of the [melting hearth" which preferably has the shape of a cup, Aso that the electric -current is forced to c1rculate completely around the melting bath, for exam le, a bath of steel to be refined, and to 5 heat ltin a uniform or adjustable manner at each single point.' Since,` as already stated, Vthe electrodes are arranged'r` on the whole circumference of the bath, that is toV say, both on its surface and also on the portions resting on the sole plate lof thehearth,

the raising of the 'electrodes arranged von the' surfaces, for the purpose of .carrying out the above'mentioned work, does not mterrupt the eurrent which continues to p assthrough the bottomv portions of the bath, so that no 'cooling of the bath can take place during the worlr in question.

In the accompanying drawingsi Figurefl shows diagrammatically a. construction of furnace, according to the present invention, in vertical section, Figs. 2 and 3 are vertical tions. F ig. L is a detail view showing the method of cooling the electrodes'. f

l is a furnace covered by an arch 2,.the hearth g of which having the sha-pe of a cup, is made of some suitable refractory material 3. In the construction illustrated, three Asections showing slightly modified construcvertical carbon electrodes a b c pass through the arch 2, while into the bottom space of the melting hearth penetrate the cooled steel electrodes d e f. lAs shown in Figs. 2 and 3, the lowermost electrodes project into` the bottoms of recesses arranged in the bottom of the' hearth.' The central of the two up? perl electrodes, namely, the electrodes b. .1

(Figs. l, 2 and 3) is connected for instance to the negative pole of a suitable-source of electricity, `and thetwo outerelectrodes a,

and c to the positivepole. -The position 'as regards the ltwo bottom onesl is a reversed f one, Vthe central electrode e being connected to the ypositive pole, while the outer ones l and f are connected to the negative pole the Same dynamo or current source being employed for the upper and lower electrodes.v Owing to this arrangement of electrodes, the current is forced first to pass from the central upper velectrode I) through the slag cover h and the upper portion of the steel bath tothe electrodes a and c. from the central bottom electrode c to the oute'ri bottom electrodes el and f, whereby the liquid steel situated at the bottom is also maintained hot. Moreover, owing to the current being forced to pass from the outer carbon electrodes aand c to the outer steel electrodes al and at the bottom, the bath itself is, so to say, completely surrounded by electric currents of suitable heating power, and at the same time a partial current circulating between the electrodes Z) and e passes Secondly,

everywhere maintained uniformly hot and does not get cooled at the walls. In that way, the formation of crust is prevented.

The importance of the surrounding admission of current to the outer surfaces of the bath in a closed circuit and along the walls, must/not be underestimated in view of the sinallness of the charges of electric furnaces where crust is easily 'formed owing to the mass of steel being small compared to the cooling mass of furnace. Another advantage of the current ,circulating inthe steel bath is the excellent mixing of the steel bath, and the obtaininent of a thoroughly uniform final product, as the current acts like a stirring d evice. ever, that, owing to this arrangement of electrodes, a very good heating of the slag cover is insured, whereby the sainebecoines very fluid and capable of easily entering into reactions. It is obvious that the duration of the refining period is thus considerably reduced and a thorough refining retained.

Owing" to the cup-shaped form of the hearth. a comparatively large surface is formed and consequently the required large surface of contact between the steel bath and 3W the slag cover is obtained in spite of the small quantity of liquid steel. Further in accordance with this invention, the difficulty increased by giving a slow rocking motion to the furnace during the refining process, whereby a thorough contact of the slag which is hot and fluid and therefore easily capable of entering into re-action with the also hot steel, is obtained, and thus the refining action of the slag is still further iiicreased. i

rIhe construction of the furnace shown in Fig'. 2, differs from the construction shown in Fig. l only by the shape of the melting hearth being a different one. namely a T- shaped one, whereby the surface of contact of the material to be melted with the refining slag cover covering the same, is increased in a manner favorable to refining. lVith this is also combined the greater facility of i The chief point is how-` cover covering the same is increase in a slag manner favorable to refining. lith this is A also combined the greater facility of expelling gases, and as the electric current has t0 follow a longer path, a higher degree of heat can be attained.

The electrodes che, f, of -the electric furnace arel preferably made of steel andas illustrated lin Fig. 4 are made hollow"in order to enable them to be cooled by a circulation of water, which is introduced through the pipe 4 and discharged through a pipe 5.

That I claim is:

rl. An electric hearth furnace having a melting hearth adapted for refining purposes, and clectrodesof alternating polarity, the bath contacting ends of said electrodes being arranged about the bath in said hearth with some of said ends at a different elevation to others thereof of unlike polarity,

whereby they electric current is forced to pass substantially vertically through and about the bulk of the material contained in said hearth.

2a. In an electric furnace, a hearth, cai-bon electrodes arranged above the hearth, and electrodes of steel in the base of the hearth, adjacent electrodes differing in' polarity throughout the hearth.

3. In an electric furnace, a hearth, noninetallic electrodes arranged above the hearth, and metallic electrodes in the base of the hearth, adjacent electrodes differing in polarity throughout the hearth.

4. In an electric furnace.. a hearth, a plurality of electrodes of differing polarity arranged above the hearth, and at least one additional electrode in the base thereof, whereby the electric current is forced to pass through and about the bulk of the material in said hearth.

In testimony whereof I have signed my naine to this specification in the presence of two subscribing witnesses.

HANS NATHUSIUS.

lVitnesses:

ERNST Kirrz, ERNST Branson. 

